( Johns Hopkins scientists have discovere...)Brain's white matter -- More 'talkative' than once thought

The discovery in mouse cells, outlined in the cover story of the March issue of Nature Neuroscience, shows that brain cells “talk?with each other in more ways than previously thought.

“We were surprised to see these nerve axons talking to other cells in the white matter,?says Dwight Bergles, Ph.D., an associate professor of neuroscience at Hopkins.

The discovery focuses on oligodendrocyte precursor cells (OPCs), whose main role when they mature into oligodendrocytes is to wrap themselves around and insulate nerves with a whitish coat of protective myelin. The immature cells simply hang around and divide very slowly, waiting to be spurred into action.

To learn more about OPCs that reside in the brain’s white matter, the Johns Hopkins researchers measured activity from individual precursor cells in the corpus callosum, a region of white matter that connects the two brain hemispheres. To their surprise, OPCs were found to have electrical signals produced by the neurotransmitter glutamate, similar to the signals used as the principle means of cell-to-cell communication and information processing in the gray matter. The phenomenon was unlikely, they said, because in the mouse brain, OPCs in the myelin-rich white matter are far from synapses, the points of contact between nerves where glutamate is released.

Theorizing that OPCs might have experienced glutamate in some less obvious way in this area of the brain, Bergles and his team studied nearby nerve cells to figure out where the glutamate might be coming from.

By forcing single nerve cells to become excited one at a time, they discovered that as electrical impulses are carried along the nerves, glutamate is released and caus
'"/>

Source:Johns Hopkins Medical Institutions